“…Cruden & Markovetz, 1987; Kaufman et al ., 1989; Breznak & Brune, 1994) and are involved in methanogenesis and nitrogen fixation (Hackstein & Stumm, 1994; Nardi et al ., 2002). The gut microflora is also implicated in pheromone production (Byers & Wood, 1981; Dillon et al ., 2000), vitamin synthesis (Chararas et al ., 1983), pesticide degradation (Boush & Matsumura, 1967), and there is evidence that gut bacteria can prevent the growth of some insect pathogens (Dillon & Charnley, 1995). As well as making use of bacteria in the gut lumen, it has been estimated that around 55 000 insect species harbour endosymbiotic bacteria within specialized host cells; these bacteria provision their hosts with nutrients that are often lacking from their diets (Wilkinson, 2001).…”